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Applying the pulsed ion chamber methodology to full range reactor ...

Applying the pulsed ion chamber methodology to full range reactor ...

CHAPTER W EXPERIMENTAL

CHAPTER W EXPERIMENTAL PROCEDURES, RESULTS AND METHODS OF DATA PROCFS3 T NO Ini tial S,y stem Setup The limiting factor of the sampling rate of the system described in the previous chapter was the analog co digital conversion speed of com- ponents used. One complete data reading required 250 msec. Because of this limit the system's pulse rare was set at 1,55/sec. The high voltage pulse width was set at 15 msec, which, was more than sufficient to sweep the chambers free cf the ions '.-'hicri constituted the steady state charge density. The collection time for the Ne ions in the RSN-34A-M1 chamber, with a 200 volt: collection potential applied, was 100 usee. For the Ar-N^ chambers, with a 300V collection potential i- applied, the "ion collection time was found to be 130 usee. A time of 630 msec was allowed for the Wiization in trie chamber to reach its equilibrium value. This was found to be more than sufficient, since the ionization density reaches its steady state value in less than 100 msec. The maximum possible collection potentials were used in each case to ensure rapid collection cf the ions. The neon filled chambers had 200 volts applied, because, above 235 volts, their response was observed to suffer from breakdown. The Ar~N ? filled chambers were operated at 350 volts, because as stated earlier, that was the upper limit of the HVP The system was run continuously for two months, with linearity, gain and zero drift being monitored periodically during that time. The lirearit.